There exists a widespread demand for decorative building materials and surfaces such as interior or exterior tiling, cladding, facing brick, and surface tops (e.g. worktops, table tops, and the like) to provide aesthetically pleasing internal and external environments. Traditional materials such as sheet stone (e.g. stone cladding) and ceramic tiling has commonly satisfied this demand. However, a rising awareness of the finite supply of mineral resources and the ever increasing quantities of landfill waste, has led to the innovation of new, more sustainable composite materials which incorporate household and industrial waste materials. Moreover, since raw materials are typically transported over long distances in order to produce the relevant decorative building materials, there is a need to address the cost and energy burden this imposes.
More sustainable composite materials include Corian® (commercially available from Du Pont) and Silestone® (commercially available from Cosentino).
Corian® is a solid, non-porous material comprising about 33% acrylic resin (PMMA—polymethyl methacrylate) and about 66% natural minerals (e.g. aluminium trihydrate). Corian® is supplied as sheets or in shaped form.
Silestone® is a dense, non-porous stone-like material comprising about 93% pulverized quartz, with the remainder being constituted by resin binders (unsaturated polyester resins) and pigments. The resin binders harden with the quartz to duly bind together the quartz aggregate.
Though Corian® and Silestone® are successful products, the inventors recognised a need for alternative composites with improved environmental sustainability. In particular, Corian® and Silestone® composites are not straightforward to recycle, since both contain binders which must first be removed in an expensive and laborious pre-treatment step before they can be effectively recycled. As such, waste Corian® and Silestone® tends to be destined for landfill due to the uneconomical recycling process. Moreover, though Corian® and Silestone® products do incorporate some waste/recycled raw materials, the total waste content is less than 75 wt %.
It is therefore an object of the present invention to solve at least one of the problems of the prior art.
Another object of the invention is to provide a composite material with improved recyclability.
Another object of the invention is to provide a composite material with a higher waste/recyclate content than those of the prior art, whilst still maintaining the structural integrity and aesthetic qualities of the composite material.
Another object of the invention is to make use of waste materials (such as cathode ray tubes) which would be otherwise destined for landfill or low-value applications (e.g. in roads).
Another object of the invention is to provide a composite material displaying unique aesthetic qualities, and that can be modified to produce a diversity of aesthetic and textural appearances.
Another object of the invention is to provide a composite material which has easier processing requirements, especially in the production of a shaped item (e.g. a tile). For example, an object of the invention is to provide a composite material which may be casted (e.g. into a shaped item) such that it retains its profile and texture upon heating (thereby not necessarily requiring a firing support mould). Moreover, an object of the invention is to provide a composite material which, after heating (e.g. during formation of a shaped item), does not require annealing during cooling, thereby enabling more efficient heat recover, rapid cooling with water, and higher throughput rates through a kiln.